Does anyone have any practical experience of using a see saw shutter? I am hoping to use the one pictured on my quarter plate Instantograph once the film arrives. I am guessing that the speed delivered by a full squeeze on the bulb to be around 30th sec. Can anyone bear this out for me I wonder. Also I have worked out that to use the shutter on B you flip over the switch at top left to stop the see-saw arm going through its full travel. But when the exposure time has finished it looks like you have to move this out of the way manually to let the arm complete its travel. There is a possibility of camera movement here or am I missing something obvious?